Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. Pacemakers and Implantable Cardiac Defibrillators (ICDs) have proven highly effective in the treatment of a number of cardiac conditions (e.g., arrhythmias). Spinal Cord Stimulation (SCS) systems have long been accepted as a therapeutic modality for the treatment of chronic pain syndromes, and the application of tissue stimulation has begun to expand to additional applications such as angina pectoris and incontinence. Deep Brain Stimulation (DBS) has also been applied therapeutically for well over a decade for the treatment of movement disorders and epilepsy. Further, in recent investigations Peripheral Nerve Stimulation (PNS) systems have demonstrated efficacy in the treatment of chronic pain syndromes, and a number of additional applications are currently under investigation. Furthermore, Functional Electrical Stimulation (FES) systems such as the Freehand system by NeuroControl (Cleveland, Ohio) have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.
Various of these implantable neurostimulation systems typically include one or more electrode-carrying stimulation leads, which are implanted at the desired stimulation site, and a neurostimulator implanted remotely from the stimulation site, but coupled either directly to the stimulation lead(s) or indirectly to the stimulation lead(s) via a lead extension. Thus, electrical pulses can be delivered from the neurostimulator to the electrode(s) to stimulate the tissue and provide the desired efficacious therapy to the patient. A handheld patient programmer may be utilized to remotely instruct the neurostimulator to generate electrical stimulation pulses in accordance with selected parameters or stimulation sets. The handheld programmer may, itself, be programmed by a technician attending the patient, for example, by using a Clinician's Programmer Station (CPS), which typically includes a general purpose computer, such as a laptop, with a programming software package installed thereon. The CPS may also be used to program the neurostimulator directly.
In a typical procedure, such as an SCS procedure, the stimulation lead(s) are introduced into the patient in contact with the target tissue under fluoroscopy. After proper placement of the lead(s) at the target area of the spinal cord, the lead(s) are anchored in place, and the proximal ends of the lead(s), or alternatively lead extensions, are passed through a tunnel leading to a subcutaneous pocket (typically made in the patient's abdominal or buttock area) where a neurostimulator is implanted. The lead(s) are connected to the neurostimulator, which is programmed with the stimulation parameter set(s). Using the CPS and/or handheld patient programmer, the neurostimulator may be operated to test the effect of stimulation and, if necessary, adjust the programmed set(s) of stimulation parameters for optimal therapy based on verbal feedback from the patient. Based on this feedback, the lead position(s) may also be adjusted and re-anchored if necessary. Any incisions are then closed to fully implant the system.
Prior to permanent implantation of the neurostimulator (as described above), the patient will typically undergo a neurostimulation trial period, which involves a brief test stimulation period in the operating room and an evaluation period of several days at home. During the test stimulation period in the operating room, stimulation energy may be delivered to the electrodes of the lead(s), while the patient provides verbal feedback regarding the efficacy of the stimulation, to verify that the lead(s) are stimulating the target neural tissue. Stimulation energy is also delivered to the electrodes at this time to formulate the most effective set of stimulus parameters, which include the electrodes that are sourcing (anodes) or returning (cathodes) the stimulation pulses at any given time, as well as other parameters, such as the magnitude, duration, and frequency of the stimulation pulses. The best stimulus parameter set will typically be one that provides stimulation energy to all of the target tissue that must be stimulated in order to provide the therapeutic benefit (e.g., pain relief), yet minimizes the volume of non-target tissue that is stimulated.
Rather than using the implantable neurostimulator to deliver the stimulation energy to the lead(s), the trial is typically performed with the use of an external trial stimulator (ETS), which provides the same stimulation functionality as the implantable neurostimulator, but is intended to be worn by the patient during the evaluation period at home. The CPS may be utilized to modify the characteristics of the stimulation output by the ETS, and to ultimately program the ETS in accordance with the selected parameters or stimulation sets.
As a result of the fast growing SCS market and neuromodulation market in general, several different neurostimulators have been developed both across the entire market and within each company. Thus, the physician often has a multitude of available neurostimulators from which to select, any of which may provide the optimum treatment for the patient. For example, Advanced Bionics Corporation markets a Precision® neurostimulator, is in clinical trial with the Bion® microstimulator, and is developing a multi-electrode Bion® microstimulator. Medtronic, Inc. markets a Synergy® neurostimulator and a Restore® neurostimulator. Advanced Neuromodulation Systems markets a Genesis® neurostimulator and an EON® neurostimulator.
Each of these devices requires its own ETS to optimize programming and replicate the appropriate implantable device. For example, the Precision® neurostimulator has a constant current source hardware platform with sixteen independent current sources that can independently deliver constant current at different magnitudes to any combination of electrodes over multiple channels. As another example, the Bion® microstimulator has a simpler, but smaller, constant current source hardware platform that can deliver current at equal magnitudes between two electrodes over a single channel. Both of the Synergy® and Restore® neurostimulators deliver electrical energy at a constant voltage, with the Synergy® neurostimulator having two voltage sources and the Restore® neurostimulator having a single voltage source. Both of the Genesis® and EON® neurostimulators have single constant current sources. As can be appreciated, all of these products require dedicated ETSs, and as such, there is no single ETS that can emulate all of these neurostimulators. In addition, the software package used by the CPS to program a particular ETS or associated neurostimulator has different features, parameters, structures, and abilities, and thus, different software packages are required for the ETSs and associated neurostimulators.
While the use of dedicated ETSs and programming software packages do not necessarily create a problem during the trialing period when it is known which type (make and/or model) of implantable neurostimulator will provide the best treatment solution for the patient at the beginning of the trial period, more likely than not, this information is not known. That is, the only realistic way to determine which neurostimulator is the best option is to actually perform a trial for each one on the patient. The current solution is to switch ETSs when trialing the devices in the operating room, and based on patient feedback, selecting the ETS, and thus, the neuromodulation device, that optimizes the therapy. In this manner, the patient need not schedule a return visit to the operating room or clinician's office to replace the ETS if the therapy is not optimum.
However, this requires the physician to maintain several ETSs in the operating room. In addition, after each ETS is switched, the corresponding programming software package must be opened (executed) on each CPS. Each programming software package takes time to load and configure, as the use of a new programming software package requires the re-entry of patient data. This, in addition to the physical switching of the ETSs, may add a significant amount of time to a given procedure, increasing the risk factors of the operation and decreasing patient and physician interest in the particular therapy intended to be delivered by the neurostimulation device.
There, thus, remains a need for an improved method and system for trialing different neurostimulation devices.